KNOWLEDGi:. 



August, 1912. 



fmiii fifty tii a hundred ;in<l rarely exceeds the 

 latter iiuinher, whereas in the latter, the number of 

 discal llorets ranj^es from one hundred to one hundred 

 and lifty-five, and rarely sinks below one hundred. 

 Moreover, the rayed florets are broader and shorter. 

 For some reason not exjilained many composite 

 flowers at a hi,t,'h le\el tend to develop their raved 

 florets. 



.Ml over the North of Italy the common ox-eye 

 daisy has an enormous majority of flowers with 

 twenty-one rays. In the same localities in the 

 autumn, towards the termination of the flowering 

 season, two sub-maxima occur, consisting of com- 

 paratively dwarfed flower-heads on non hnmchln{< 

 plants, in which the great majority of rayed florets 

 are resjiectively eight and thirteen in number. 



On the other hand a little after the beginning of 

 the flowering season, at high levels, on garden soil, 

 facing south, plants can be found with a large 

 majority of flower heads, with rayed florets thirty- 

 four in number, which is the ne.xt phyllotaxis 

 number above twenty-one. I demonstrated this 

 with the utmost certainty, in the case of ox-eye 

 daisy growing in high level localities, near Rovena 

 above Cernobbio. Lago di Como. On Monte Grigna, 

 the Eastern or Lecco branch of the lake, occurs at 

 still high levels a rare and gigantic species called, if 

 I mistake not, Clirysantliemiiin iiiibricatiiiii, which 

 doubtless has thirty-four and perhaps fifty-five elon- 

 gated rayed flowers, but I have not as yet obtained 

 specimens. Another instance, however, of the 

 development of the ray florets is the wild .\rnica. 

 which occurs at comparatively high levels, not as a 

 rule below four thousand feet, on pastures (above 

 Brunate, Lago di Como) or on marshy meadows 

 (Tonale Pass, \'al Camonica). In valleys by slow- 

 running rivers and in other similar localities just the 

 ojiposite occurs. The rayed florets become broad, short 

 and few in number or disappear altogether, w bile the 

 number of the discal florets increases. A common 

 instance of this is GaUinso^a canadensis, found all 

 over the North of Italy, and also in the South of 

 England, where it was introduced about thirtv 

 years ago, and rapidly spread down the Thames 

 Valley from Kew to Oxford. In this plant the 

 rayed florets are reduced to invariably five in 

 number (liroad and scale-like) having been crowded 

 out b\- the discal florets which form a thick convex 

 tO|)knot. In the common tansv {Tanaccfiini viili^arc) 

 which haunts the banks of low-level or comparativelv 

 low-level rivers, the rayed florets have disappeared 

 altogether, and the discal ones become numerous and 

 close packed. Tanacefiint viiliiare is never found 

 with its distant relation the romantic edelweiss in 

 its ideal sites of snow and ice. .\ perhaps still more 

 remarkable instance occurs in .\ustralia and New 

 Zealand. In troj^ical and hot sub-tropical countries 

 composites are not as a rule plentiful : thus in New 

 Zealand, i.e., in the North Island and in Eastern 

 .Australia (for strange to say in hot Western .Australia 

 there is a wonderful developinent of novel forms of 

 composites) there is only one that strikes the eve, a 



small creeping plant, growing in moist spots, and 

 lush water-me;idows, with flcjwer buttons similar to 

 those of the tansy, l)Ut smaller and mf)re hygro- 

 phanons. On the other hand in the almost sub-.\rctic 

 and rugged Stewart Island, there are several com- 

 jKisite shrubs and small trees, the flowers of which 

 abound in rayed florets. 



To sum up the results so far as indicated by the 

 above remarks. In all composite flowers with rays, the 

 number of which does not greatly exceed thirty-four, 

 the vast majority of flowers have two (rare), three, five, 

 eight, thirteen, twenty-one and thirty-four rays, or, 

 in some few cases, double eight and double thirteen 

 i.e.. sixteen or twenty-six. .Again, in a few plants of 

 w hich the florets are all liguled, and not differentiated 

 into rayed and discal ones, <;.^'.. in chicories and 

 prenanthes, the flowers represent two rings of the 

 concentric ring system, beginning with a ring of five, 

 or more rarely one of the rings (five or eleven) or again 

 one ring (five) and part of the second or two rings 

 (five and eleven) and part of the third. As regards 

 the discal florets of composite flowers differentiated 

 into disc and corona, nothing has so far been said. 



Some years ago I attempted to estimate, at 

 Cernobbio, the number of discal florets of the small, 

 late autumn form of theox-eve daisy with thirteen rays, 

 by counting the number of discal florets in a cross 

 section of the disc or eye. but soon found that to 

 estimate the number of discal florets in a closely- 

 packed disc like that of the ox-eye daisy was an 

 impossibility, or, at any rate, a perfectly futile waste of 

 time ; because, owing to crowding, numbers of florets 

 were reduced to pin points, or crowded out of existence 

 altogether, so that an estimate of what remained 

 could only yield statistics on which no sound reason- 

 ing could be based. I therefore turned m\ attention 

 to the small wild calendula, abundant in most coast 

 regions all down the Italian Peninsula. The observa- 

 tions were made at Taormina, on what may almost 

 be called a gigantic scale, and resulted in the 

 demonstration of a law so simple and yet so wonder- 

 ful, that even now, although the evidence is over- 

 whelming, I still regard it with a modicum of 

 scepticism. I shall reserve the enunciation of it 

 until the whole voluminous series of observations are 

 published, when, if they ever are published, the 

 law in question will excite wonder, astonishment 

 and delight in everyone not dead to these 

 sentiments and emotions. F'or the i)resent I 

 confine myself to a general statement that in the 

 calendulas, as in the chicories and prenanthes. the 

 discal florets are arranged in concentric rings of florets 

 in a majority of the flower heads. 



The other day, some plants of Senecio jacoboea 

 (common ragwort) reminded me that this is one of 

 the very few composites the flower-heads of which 

 have almost invariably thirteen rays, more exactly 

 ninety-eight per cent, and a fraction, so that this 

 plant inay claim a certain communit\' of ideas with one 

 of the pseudo-cycads. the flower of w hich. a thirteen- 

 rayed star, was figured in " KNOWLEDCii " (May, 

 lyiO, page 174), and of interest as supposed to be 



